Improving the moisture stability of perovskite solar cells by using PMMA/P3HT based hole-transport layers

Abstract

In recent years, the performance of lead halide perovskite solar cells has increased dramatically, setting a record efficiency of 22.1%; however, their sensitivity towards water limits their utility and still needs to be addressed. While many different materials and methods are being developed to solve this problem, recent studies have suggested that modifications to the hole-transport layer can be effectively used to improve device stability. In this study, we report a new device architecture that makes use of a poly(3-hexylthiophene) (P3HT) nanowire network in a poly(methyl methacrylate) (PMMA) matrix as the hole-transport layer. The PMMA matrix imparts excellent resistance toward the ingress of both liquid and vapor-phase water, and leads to a large increase in the stability of the device. Using a combination of in situ absorbance spectroscopy, powder X-ray diffraction and device measurements, we have quantified the increase in device stability; optimized PMMA/P3HT layers can improve device lifetimes by an order of magnitude.